Implication of the Whitefly, Bemisia tabaci, Collagen Protein in Begomoviruses Acquisition and Transmission.

Begomoviruses are the largest group of plant viruses transmitted exclusively by the whitefly, Bemisia tabaci (Gennadius), in a persistent, circulative, and nonpropagative manner. Begomoviruses in association with B. tabaci cause enormous loss to world agricultural crops. Transmission, retention, and circulation of begomovirus in B. tabaci are facilitated by its interaction with several proteins of the insect and its endosymbionts. However, very few such proteins have been identified from B. tabaci that are involved in this specific interaction. Here, we have performed yeast two-hybrid assay between B. tabaci complementary DNA expression library and the coat protein (CP) of tomato leaf curl New Delhi virus (ToLCNDV) and cotton leaf curl Rajasthan virus (CLCuV). Collagen was the common protein found to be interacting with both of the viruses. The collagen protein was found to be localized in gut layers of B. tabaci. Additionally, pull-down and dot-blot assays confirmed the association of endogenous collagen with ToLCNDV CP. Immunolocalization analysis also showed colocalization of ToLCNDV particles and collagen within insect gut. Finally, B. tabaci fed on anticollagen antibody and exhibited ∼46% reduction in ToLCNDV transmission, suggesting a supportive role for collagen in virus transmission.